Learn Mocha, Mongoose and Twit

In this course we’ll learn how to create Twitter bots. We’ll first learn how to interface with the Twitter API using Twit.js, which allows us to post statuses, search tweets, and interact with followers. We’ll create several example bots that show the diversity of possibilities, using powerful tools such as RiTa.js, Google’s Cloud Vision API, and Tracery. We’ll learn how to tweet data from Google Spreadsheets, and to compose and tweet a song for an audio bot. We’ll also learn how to host our bot logic on Heroku and Docker. 

Twitter API Client for node

Supports both the REST and Streaming API.

twit

Create your own twitter bots

Mongoose provides a straight-forward, schema-based solution to model your application data. It includes built-in type casting, validation, query building, business logic hooks and more, out of the box.

mongoose

One of the great things about NoSQL databases is that you do not have to decide on your data schema while developing. As you get closer to production though, you'll often want to more clearly define the shape of the data you are working with.

Enforce Schemas in MongoDB using Mongoose Models

We’ll get a real-time stream of tweets, and learn how to filter a stream by keyword, location, and user.

Use the Twitter Stream API with Twit.js

Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.

express

Mongoose allows you to easily select resources by ID from your MongoDB. This is an important aspect to creating an API.

Select by ID with Mongoose and Express

Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple and fun. Mocha tests run serially, allowing for flexible and accurate reporting, while mapping uncaught exceptions to the correct test cases.

mocha

Every dependable library needs to have tests to ensure that you don't push accidental bugs. In this lesson, see how you can set up mocha and chai to start testing your library.

Setting up Unit Testing with Mocha and Chai

Now that you've got everything set up with mocha and chai, it's time to actually write tests. In this lesson you'll learn how to use `describe` and `it` to outline your tests and make sure you don't break your library in the future.

Unit Testing with Mocha and Chai

Mocha is a testing framework that provides structure for unit tests. In this lesson, we will be setting up Mocha with npm and npm scripts, writing a "Hello World" unit test, then writing the code to make the test pass (as an example of Test Driven Development (TDD), with the "red-green-refactor" workflow).

JavaScript Testing Fundamentals: Hello world unit test with Mocha (in ES6)

In this lesson, we will use Chai's request method to test our Node application's API responses.
By the end of this lesson, you will know how to:
- install the prerequisites to use mocha and chai in your application
- test for HTTP status response codes
- test for a string of text on a page
- test for a json response and validate the properties of the object
- write tests that not only verify the response of your application, but the behavior as well


Test Node RESTful API with Mocha and Chai

In this lesson, our bot will tweet hello to the Twitter world! We'll do this by using Twit's POST method to post our status to the statuses/update endpoint.

Post Statuses with Twit.js

Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework.

chai

Writing great ES6 style Promises for Node.js is only half the battle. Your great modules must include tests as well to ensure future iterations don't break them. In this lesson, I show you a simple ES6 Promise in Node.js, then walk you through creating tests in Mocha using chai and chai-as-promised to test both resolve and reject methods.

Testing ES6 Promises in Node.js using Mocha and Chai

In this lesson, we’ll create multiple functions to request, download, and save photos and data from NASA's API, and then have our bot upload these photos to Twitter and post them along with their descriptions. We'll also learn how to tweet videos using a video from NASA’s space archives.

Tweet Media Files with Twit.js

We’ll learn how your bot can get its list of followers, follow people, and look up friendships. We'll use Twit's GET method to get our followers at the followers/list endpoint, to get the users we follow at the friends/ids and friends/list endpoints, and to look up our friendships with the friendships/lookup endpoint. We'll also use Twit's POST method to follow someone at the friendships/create endpoint, and to send messages by posting to the direct_messages/new endpoint. 

Work with Users in Twit.js

We’ll learn the basics of interacting with tweets, including retweeting, deleting, favoriting, and replying to tweets. We'll get our home timeline by using Twit's GET method to access the `statuses/home_timeline` endpoint, including the count parameter, which lets us get back a certain number of tweets. We'll also pass it a callback. We'll learn how to cycle through the data (the tweets) we get back and see what information is included. We'll learn how to retweet statuses by posting to `statuses/retweet` and including the tweet id. We can unretweet by posting to `statuses/unretweet` with the same tweet id. We'll also learn how to like a tweet by posting to `favorites/create` with a tweet id, and unlike a tweet by posting to `favorites/destroy` with a tweet id. We'll also learn how to reply to a tweet by posting to `statuses/update`, with a status that includes the handle of the user we're replying to and `in_reply_to_status_id` parameter, which is the id of the tweet we're replying to. We'll learn how to delete a tweet by posting to `statuses/destroy` with the tweet's id. 

Interact with Tweets with Twit.js 

We’ll learn how to search tweets with the Twitter Search API, using Twit's GET method to get the search/tweets endpoint. We'll use the query and count parameters to get the search term(s) and number of tweets that we want. We'll learn how to get exact phrases, multiple words, one of several words, emoticons, hashtags, photos/videos, urls, and how to remove words from our results. We'll learn how to implement the safe filter and how to filter by media, website, or date. We'll learn how to get recent results, popular results, results by location, and results by language. 

The search API returns for relevance, and not completeness. If you want all the tweets from a search term, you should use the stream API (which we'll go over in the next lesson). 

Use the Twitter Search API with Twit.js

We’ll go over the basic Twitter bot setup, including how to start a project from scratch, install necessary packages, and store our private keys in environment variables. 

Set Up a Basic Twitter Bot with Twit.js

In this lesson, you will learn how to verify your API server is returning HTTP 400 responses when clients submit incorrect data. Returning HTTP 400 ensures that your clients are notified of the incorrect usage. Testing for them ensures your API returns errors instead of incorrect responses when supplied with incorrect data.

Test for HTTP 400 responses with Mocha and Chai

Unit testing functions that invoke callbacks can require a lot of setup code. Using `sinon.spy` to create a fake callback function can simplify your unit tests while still allowing you to observe the output of the function you're testing.

Unit Test a Function that Invokes a Callback with a Sinon Spy

When testing functions that make HTTP requests, it's not preferable for those requests to actually run. Using the `nock` JavaScript library, we can mock out HTTP requests so that they don't actually happen, control the responses from those requests, and assert when requests are made.

Mock an HTTP request using Nock while unit testing

When mocking a JavaScript function during a unit test, it can be helpful to force a mock function to return a value of your choosing. This allows you to verify that functions you're testing will behave correctly for every possible use case.

Much like [`sinon.spy()`](https://sinonjs.org/releases/v7.0.0/spies/), [`sinon.stub()`](https://sinonjs.org/releases/v7.0.0/stubs/) creates a mock function that prevents a real function from running. But, unlike `spy`, it also allows you to declare what value you'd like the mock function to return.

Mock a function's return value using a Sinon stub

Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.

node

Sometimes when writing a unit test, you know that the module you're testing imports a module that you would like to observe, or at the very least mock to prevent side effects like network activity or file system operations.

For JavaScript unit tests that run in Node, we can hijack the built-in `require` function by using the [`proxyquire`](https://www.npmjs.com/package/proxyquire) module, which allows us to mock one or more modules that are second-class dependencies in our unit test, replacing them with whatever we want.

This means we could replace functions with [no-ops](https://en.wikipedia.org/wiki/NOP_%28code%29) to prevent side effects, or replace them with [Sinon spies](https://egghead.io/lessons/mocha-unit-test-a-function-that-invokes-a-callback-with-a-sinon-spy) to observe the inner workings of the module you're testing.

In this video, we'll demonstrate the basics of using Proxyquire to prevent and observe a file system operation.

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